<p>
Nothing is known about the ring structure except in the case of level 2:
<div class="literature">
            <ul>
              <li><span class="name">
Ibukiyama and F. Onodera</span>
On the graded ring of modular forms of the Siegel
paramodular group of level 2, Abh. Sem. Univ. Hamburg 67 (1997), 297-305
(Look up math review)
		</li>
	</ul>
</div>
The above paper is not needed because the dimensions are calculated by
the  general dimension formula for weights 3 and higher.
(See the basic information page.)
</p>
